NO. 9 MUSCULATURE OF THE BLUE CRAB COCHRAN 49 



It runs inward without narrowing to its insertion along the proximal 

 posterior wall of the basipodite, which is moved backward by its 

 action. 



117 . Miisculus abductor e.vopoditis I pedis spurii (fig. 14 C). — 

 Arising on the lateral anterior border of the basipodite near the inser- 

 tion of the abductor of the basipodite, the abductor of the exopodite is 

 inserted on the lateral wall of the exopodite, on which it produces a 

 feeble outward pull. 



lyS. Miisculus adductor e.vopoditis I pedis spurii (fig. 14 C) . — This 

 rather slender muscle arises on the median proximal preaxial wall of 

 the basipodite and extends outward to its insertion on the inner proxi- 

 mal end of the exopodite, which is moved inw^ard by its pull. 



There are no muscles to govern the endopodite, which moves only 

 as the basipodite moves. 



i/p. Musculus promotor coxopoditis II pedis spurii. — See //j. 



180. Musculus abductor coxopoditis II pedis spurii. — See 1I4. 



181. Musculus adductor coxopoditis II pedis spurii. — See 775. 



182. Musculus reductor basipoditis II pedis spurii. — See //d. 

 i8j. Musculus abductor cxopoditis II pedis spurii. — See 177. 



184. Muscidus adductor cxopoditis II pedis spurii. — See 178. 



185. Musculus promotor coxopoditis III pedis spurii. — See 173. 



186. Muscidus abductor coxopoditis III pedis spurii. — See 174. 



187. Muscidus adductor coxopoditis III pedis spurii. — See 175. 



188. Musculus reductor basipoditis III pedis spurii. — See 176. 

 i8p. Muscidus abductor cxopoditis III pedis spurii. — See 177. 

 ipo. Musculus adductor cxopoditis III pedis spurii. — See 178. 

 ipi. Musculus prcmiotor coxopoditis IV pedis spurii. — See i/j. 

 1^2. Musculus abductor coxopoditis IV pedis spurii. — -See 174. 

 jpj. Musculus adductor coxopoditis IV pedis spurii. — See 17$. 

 ip4. Musculus reductor basipoditis IV pedis spurii. — See 176. 

 ip^. Musculus abductor cxopoditis IV pedis spurii. — See 177. 

 ip6. Muscidus adductor cxopoditis IV pedis spurii. — See 178. 



The Skeleton 



A brief survey of some of the skeletal peculiarities found in the blue 

 crab is not out of place in a study of its myology, since the shape of 

 the skeleton and the arrangement of the muscles attached upon it are 

 mutually interdependent. 



The segments of the head and thorax of the crab are immovably 

 ankylosed, as I have repeatedly emphasized. To some extent, this 

 fact simplifies the musculature, as it at once precludes the presence of 



